It’s always a bad hair day for Susan Boyle — until she starts to sing.

The Scottish songbird with the frizzed-out hair doesn’t look like a star — she’s chubby, with plain features and no thousand-watt showbiz smile. But her golden voice has made her the overwhelming favourite in Saturday’s Britain’s Got Talent finals, expected to draw millions of viewers in Britain, where it’s broadcast live, and tens of millions throughout the world, with the help of YouTube and other online sites.

If she can prevail over nine competitors, the overnight singing sensation from a hardscrabble village in Scotland would pocket 100,000 pounds (C$178,000) and an invitation to perform at a Royal Variety Show in front of the Queen.

With her high-profile fans — including actress Demi Moore, expected to jet in for the finals — and an appearance on the Oprah Winfrey show, Boyle has far overshadowed the other contestants. But she still must excel Saturday night and hope that none of her rivals generate enough magic to win over the frequently fickle British public.

“I think with the swell of public sympathy behind her, she could win this competition, and from that I think she could have a very successful album and probably one successful world tour because people will be curious to see her,” said Neil Warnock, chief executive of The Agency Group, which represents dozens of top musicians.

He cautioned, however, that fame may be fleeting.

It will be much more challenging, he said, for Boyle to perform an entire live show on a concert tour than to sing one three-minute number on TV.

Even if she stumbles, a professional career seems likely. She’s been offered a recording contract and her huge name recognition would give any debut offering a fighting chance. But a poor performance Saturday might relegate her to flash-in-the-pan status in a disposable celebrity culture that makes and breaks stars at warp speed.

The hugely successful talent show has its roots in Britain’s music hall tradition, which brought performing dogs, ersatz magicians, ventriloquists and fire-eaters to hundreds of towns and villages in the days before television. Warnock said this is part of the charm.

“We tend to make fun of the very, very stupid acts, but it has its own Englishness and its own eccentricity and we love that,” said Warnock. “And you see a spark of genuine talent every once in a while.”

The ten finalists all have stars — and dollar signs — in their eyes. But the real financial rewards will have to wait until after the competition. Boyle has already had phenomenal success on YouTube, where her first round performance has generated more than 175 million views, but those legions of fans do not bring her any cash.